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Fixed #12886 -- aggregation over sliced queryset

This commit is contained in:
Anssi Kääriäinen 2013-08-19 16:00:17 +03:00
parent 7d28bed13b
commit 7737305a4f
3 changed files with 14 additions and 7 deletions
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5
django/db/models/query.py
View File

@ -313,14 +313,13 @@ class QuerySet(object):
kwargs[arg.default_alias] = arg kwargs[arg.default_alias] = arg
query = self.query.clone() query = self.query.clone()
force_subq = query.low_mark != 0 or query.high_mark is not None
aggregate_names = [] aggregate_names = []
for (alias, aggregate_expr) in kwargs.items(): for (alias, aggregate_expr) in kwargs.items():
query.add_aggregate(aggregate_expr, self.model, alias, query.add_aggregate(aggregate_expr, self.model, alias,
is_summary=True) is_summary=True)
aggregate_names.append(alias) aggregate_names.append(alias)
return query.get_aggregation(using=self.db, force_subq=force_subq)
return query.get_aggregation(using=self.db)
def count(self): def count(self):
""" """

8
django/db/models/sql/query.py
View File

@ -315,7 +315,7 @@ class Query(object):
# Return value depends on the type of the field being processed. # Return value depends on the type of the field being processed.
return self.convert_values(value, aggregate.field, connection) return self.convert_values(value, aggregate.field, connection)
def get_aggregation(self, using): def get_aggregation(self, using, force_subq=False):
""" """
Returns the dictionary with the values of the existing aggregations. Returns the dictionary with the values of the existing aggregations.
""" """
@ -325,18 +325,18 @@ class Query(object):
# If there is a group by clause, aggregating does not add useful # If there is a group by clause, aggregating does not add useful
# information but retrieves only the first row. Aggregate # information but retrieves only the first row. Aggregate
# over the subquery instead. # over the subquery instead.
if self.group_by is not None: if self.group_by is not None or force_subq:
from django.db.models.sql.subqueries import AggregateQuery from django.db.models.sql.subqueries import AggregateQuery
query = AggregateQuery(self.model) query = AggregateQuery(self.model)
obj = self.clone() obj = self.clone()
relabels = dict((t, 'subquery') for t in self.tables)
# Remove any aggregates marked for reduction from the subquery # Remove any aggregates marked for reduction from the subquery
# and move them to the outer AggregateQuery. # and move them to the outer AggregateQuery.
for alias, aggregate in self.aggregate_select.items(): for alias, aggregate in self.aggregate_select.items():
if aggregate.is_summary: if aggregate.is_summary:
query.aggregate_select[alias] = aggregate query.aggregate_select[alias] = aggregate.relabeled_clone(relabels)
del obj.aggregate_select[alias] del obj.aggregate_select[alias]
try: try:

8
tests/aggregation/tests.py
View File

@ -617,3 +617,11 @@ class BaseAggregateTestCase(TestCase):
# Check internal state # Check internal state
self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type) self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type)
self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type) self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type)
def test_ticket12886(self):
"""
Check that aggregation over sliced queryset works correctly.
"""
qs = Book.objects.all().order_by('-rating')[0:3]
vals = qs.aggregate(average_top3_rating=Avg('rating'))['average_top3_rating']
self.assertAlmostEqual(vals, 4.5, places=2)